1. Field of the Invention
The present invention relates to a method for searching for an optimal temperature of an inkjet chip of a printhead, and more particularly, to a method for searching for an optimal temperature of an ink jet chip of a printhead for a predetermined swath density.
2. Description of the Prior Art
Ink jet printers provide good printing quality at a fair price and as a result, have become the most popular printing equipment. With the quick advancement of technology, better printing quality has been a target that information industrial circles work to achieve. Generally speaking, an ink jet printer, such as a bubble-jet printer, uses heating elements of the printhead to heat ink. When the energy level imparted to the heating elements is high enough, ink becomes bubbles and is jetted from the nozzles of the printhead. The ink consumes a part of the energy. However, the remaining part of the expended energy will stay in the printhead so that the temperature of the printhead increases.
After the temperature of the printhead exceeds a maximum temperature Tmax at which the printhead can operate normally, printing quality deteriorates. Therefore, most manufacturers control or limit a threshold temperature of a printer to ensure that the temperature of the ink jet chip will not exceed the maximum temperature Tmax during printing. When the printhead finishes printing a swath, the best condition is that the temperature of the ink jet chip is about the maximum temperature Tmax at which the printhead can operate normally.
When printing higher swath densities, the temperature variations of the ink jet chip are larger. That is, the temperature of the ink jet chip shows a larger growth during printing. On the contrary, for lower swath densities, the temperature variation of the ink jet chip is smaller. In other words, when printing lower swath densities, the temperature of the ink jet chip increases during printing, but the increase is less than the increase when printing higher swath densities. Of course, if the threshold temperature Tthreshold of the printhead, meaning the temperature to which the ink jet chip is preheated before commencing printing, is set to a lower temperature, this can ensure that the temperature of the ink jet chip does not exceed the maximum temperature Tmax at which the ink jet chip can operate normally. However, when printing lower swath densities using such a printhead, after finishing printing, the finishing temperature of the ink jet chip is much lower than the maximum temperature Tmax so that printing quality is poor and standby time is increased due to the smaller temperature variations and the lower threshold temperature Tthreshold. If the threshold temperature Tthreshold is set to a higher temperature in order to optimize printing quality, the temperature variations of the ink jet chip are too large when printing higher swath densities. What is worse, during printing, the temperature of the ink jet chip exceeds the maximum temperature Tmax, damaging the printhead.